This invention relates generally to touch display systems, and more particularly, to algorithms for recognizing touches on touch display systems.
Touch display systems, or “touch displays”, are provided for an increasing number of applications. Point of sale (POS), for processing transactions within a department store, and point of information (POI), such as an electronic directory are common. For example, applications include airport passenger and baggage check-in, and kiosks located within a store which provide information about products and services. The kiosks also may be used to place an order and/or complete a purchase without the assistance of a sales person.
A touch display system has a display for visually presenting data to a user. A touchscreen is installed in front of the display, and the user selects and/or inputs data by touching the touchscreen at locations over software programmed buttons or icons in the displayed image. There are a number of different technologies used for touchscreens, such as resistive, capacitive, infra-red and surface acoustic wave (SAW).
In order for the user's touch on the touchscreen to successfully interact with the display, the coordinates of the display and the touchscreen are calibrated with respect to each other. This is particularly important for graphical user interfaces (GUI) which tend to have buttons and icons of small size such as the small close box “X” of Microsoft's Windows®. To ensure a good linear correspondence between where a person touches the touchscreen and the resulting cursor location in the displayed image, a 25-point or 3-point calibration process may be completed to generate calibration constants before touchscreen-based GUI operation.
Touch displays often have bezels that extend over outer edges of the touchscreen, and thus areas of the touchscreen along the outer edges of the exposed touchscreen surface are often designed as dead zones. Insensitive areas proximate to the bezel prevent erroneous touches caused by bezel pressure on the touchscreen. Such bezel pressure may occur if the touch display is bumped, or simply result from static forces within the assembled touch display. However, the displayed GUI image may offer selection buttons or icons that fall close to or within the dead zones, or close to the bezel. It may be difficult or impossible for the user to select some GUI buttons due to the inactive touch zone as well as physical impedance from the bezel. This problem may be increasingly experienced as display applications become smaller in size, such as personal digital assistants and hand-held delivery tracking and signature gathering devices.
Therefore, a need exists for ensuring that touch display users can easily activate GUI buttons and icons near the outer edges of the exposed touchscreen surface. Certain embodiments of the present invention are intended to meet these needs and other objectives that will become apparent from the description and drawings set forth below.